The present disclosure relates generally to a controller for thermal treatment of tissue, and, more particularly, to a processor-based controller for Benign Prostatic Hypertrophy (BPH) treatment via transurethral diathermy.
Benign prostate hyperplasia (BPH) or hyperplasia affects over one out of every two males over the age of fifty. BPH is the non-cancerous enlargement of the prostate gland and is characterized generally by a constriction of the urethra by the prostate gland. An array of symptoms are associated with BPH including frequent urination, complications in urinary flow and associated pain.
Generally there are two primary methods for treating BPH, namely, drug therapy and surgical intervention. Drug therapy incorporates the use of one or more drugs such as Proscar(trademark) and Hydrin(trademark) to either reduce the size of the prostate or to relax the urethral muscles thereby facilitating the normal functioning of the urinary system. Known drug therapies, however, are limited in their effectiveness and present many drug side effect concerns.
Surgical methods for treating BPH include transurethral resection of the prostate (TURP), transurethral incision of the prostate (TUIP), visual laser assisted prostatectomy (VLAP), balloon dilation and stenting. TURP is the most common method employed for BPH treatment today and involves the insertion of an electrosurgical cutting instrument through the urethral passage. The cutting elements of the instrument are positioned adjacent the prostate gland, and the instrument is energized such that the cutting elements selectively cauterize and resect tissue from the core of the prostate. The TURP procedure, however, has many side effects including bleeding, retrograde ejaculation, impotence, incontinence, edema and a prolonged recovery period for the patient.
A more recent form of treatment for BPH involves thermally treating prostatic tissue with radio frequency (RF) electromagnetic energy. For example, one current technique, known as transurethral needle ablation (TUNA(trademark)), involves the transurethral application of a medical instrument having a built-in RF needle electrode system. The TUNA(trademark) instrument is inserted into the urethra and advanced to a position adjacent the prostate. Thereafter, the RF needles are advanced to penetrate the urethral wall and access the prostatic tissue. The RF system is activated whereby a RF current is transmitted through each electrode to pass through the tissue to a grounding pad thereby forming a necrotic lesion which is eventually absorbed by the body. Apparatuses and method for treating BPH via the TUNA(trademark) technique are disclosed for example in U.S. Pat. No. 5,366,490.
The TUNA(trademark) technique has several disadvantages which detract from its usefulness. In particular, the TUNA(trademark) instruments are generally complex typically incorporating built-in optical systems, aspiration systems, etc. As a result, the instruments are relatively expensive to manufacture. Moreover, the TUNA(trademark) instruments are generally enlarged by virtue of the various systems incorporated within the instrument, thus, increasing patient trauma and discomfort during use.
Commonly assigned U.S. patent application Ser. No. 08/699,091, entitled xe2x80x9cAPPARATUS FOR THERMAL TREATMENT OF TISSUExe2x80x9d, filed Aug. 16, 1996 (hereafter, the ""091 application), and commonly assigned U.S. provisional patent application No. 60/027600, filed Oct. 4, 1996, the contents of both of which are incorporated herein by reference, disclose highly effective apparatuses for the radio-frequency (RF) thermal treatment of prostatic tissue. The apparatus disclosed in the ""091 application is intended for use in conjunction with a conventional endoscope such as a cystoscope and incorporates an RF system and associated mechanism that is at least partially positionable within the working channel of the scope. The apparatus, by use in conjunction with a conventional cystoscope, makes use of the existing systems, e.g., optical and illumination, of the scope, which effectively results in a less complex and less expensive RF thermal treatment device. Furthermore, the apparatus may be used in cystoscopies as small as 5 mm (or even smaller) in diameter thereby providing a less invasive system for transurethral ablation as compared to the TUNA instruments and technique.
Accordingly, the present disclosure is directed to a system and controller for use in conjunction with, for example, an RF thermal treatment apparatus to facilitate operation thereof during the treatment of the BPH condition. Generally, the system includes an RF generator for outputting RF current through a first RF ablation electrode and a second electrode in contact with the patient to thereby ablate, body tissue between the two electrodes. The second electrode is preferably a plate abutting the patient""s skin for a monopolar treatment mode. Temperature measuring circuitry within the apparatus is coupled to a temperature sensor in a specific body region. An input means such as a plurality of switches on the controller housing is provided to enable a user to input a treatment volume corresponding to a target volume of body tissue to be ablated. Delivery of RF power is automatically terminated when a treatment time corresponding to the selected treatment volume is reached.
The controller may further include an infusion pump, coupled to a disposable syringe mounted within the apparatus, for pumping a fluid such as saline solution out of the syringe and into the body region being treated at a controlled rate. The fluid serves to provide a more uniform ablation of body tissue. The controller may further include impedance measurement circuitry to measure the impedance between the two electrodes. The therapy is automatically terminated if the impedance rises above a threshold value.